Main Entry : 1roof Pronunciation : 'rüf, 'rufFunction : nounInflected Form(s): plural roofs /'rüfs, 'rufs also 'rüvz, 'ruvz/Etymology : Middle English, from Old English hrOf; akin to Old Norse hrOf roof of a boathouse and perhaps to Old Church Slavonic stropu roof1 a (1) : the cover of a building (2) : material used for a roof : ROOFING b : the roof of a dwelling conventionally designating the home itself <didn't have a roof over my head> <they share the same roof>2 a : the highest point : SUMMIT b : an upper limit : CEILING3 a : the vaulted upper boundary of the mouth b : a covering structure of any of various parts of the body <roof of the skull>4 : something suggesting a roof: as a : a canopy of leaves and branches b : the top over the passenger section of a vehicle